Electric driveline system with power take-off and electric driveline system operating method

ABSTRACT

An electric driveline system is provided. The electric driveline system includes a first electric machine and a second electric machine mechanically coupled to a transmission and a power take-off (PTO) assembly coupled to the first electric machine. The PTO assembly includes a first clutch coupled to a PTO gearset and designed to selectively disconnect a PTO from the first electric machine and the PTO gearset is mechanically coupled to the first electric machine.

TECHNICAL FIELD

The present disclosure relates to a multi-speed electric drivelinesystem and a method for operation of said driveline system.

BACKGROUND AND SUMMARY

Multi-speed transmissions have been deployed in certain electricvehicles (EVs) due to their increased responsiveness and gains in motoroperating efficiency that the transmission affords when compared to EVsusing single speed geartrains. Some of these prior multi-speed electricdrive units do not have components that rotate independently from thewheels when the vehicle is at standstill. Moreover, certain electricdrivelines demand that the driveline components rotate in an oppositedirection (in comparison to forward drive) when operating in reverse.This presents barriers to implementing power take-off (PTO) capabilitiesfor driving auxiliaries when operating the driveline in reverse, atstandstill, or in forward drive at low speeds.

Some attempts have been made to provide PTO functionality into certainEVs. For instance, US 2015/0135863 A1 to Dalum discloses a hybridvehicle drive system that uses an electric motor to power a PTO which,in turn, drives accessories. The PTO in Dalum's system is not capable ofconcurrently driving both the accessories and providing motive power tothe transmission.

The inventors have recognized several drawbacks with Dalum's drivesystem as well as other electric drive systems. For instance, theinability to simultaneously drive both the PTO accessories and providemotive power to the transmission using the electric motor constrains thesystem's capabilities, thereby decreasing customer appeal. Further,other systems have employed dedicated motors and inverters toindependently power PTOs. These systems are complex and may presentmanufacturing difficulties.

The inventors have recognized the aforementioned issues and developed anelectric driveline system. In one example, the electric driveline systemincludes a first electric machine and a second electric machinemechanically coupled to a transmission. The electric driveline systemfurther includes a PTO assembly coupled to the first electric machine.This PTO assembly includes a first clutch coupled to a PTO gearset andis designed to selectively disconnect a PTO from the first electricmachine. Further, in the system, the PTO gearset is mechanically coupledto the first electric machine. In this way, the first electric machineis able to provide power to both the transmission and the PTO atoverlapping times, if wanted. As a result, the system's capabilities areexpanded via a PTO assembly that uses power from an electric machinewhich is also designed to provide motive power to the transmission.Further, the complexity and cost of the system may be reduced, ifwanted, when compared to electric drive systems which use dedicatedmotors for powering PTOs, for instance.

In another example, the electric driveline system may further include asecond clutch designed to selectively disconnect the first electricmachine from the transmission. In such an example, the system mayadditionally include a controller configured to operate the secondclutch to disconnect the transmission from the first electric machine,while the second electric machine is transferring mechanical power tothe transmission. This disconnection may occur when the second electricmachine is operated to rotate the transmission in a reverse drivedirection. In this way, the window of PTO operation with regard todriveline operating conditions is expanded, thereby broadening thesystem's capabilities and increasing customer appeal.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a portion of a vehicle with an electric driveline system.

FIGS. 2A-2B show the power paths through the electric driveline systemof FIG. 1 in a first and second gear configuration while a powertake-off (PTO) is disconnected.

FIGS. 2C-2D illustrate exemplary power paths which provide power to thePTO of the electric driveline system, depicted in FIG. 1 .

FIGS. 2E-2G show charts correlating the various electric drivelinesystem operating modes to clutch and synchronizer positons.

FIG. 3A-3C show mechanical, hydraulic, and electrical connections,respectively, in an electric driveline system of a vehicle.

FIG. 4 shows a method for operation of an electric driveline system.

DETAILED DESCRIPTION

An electric driveline with a multi-speed transmission and power take-off(PTO) disconnect capabilities is described herein. The PTO disconnectcapabilities are achieved using a PTO assembly with clutches thatfunction to selectively connect and disconnect a PTO from an electricmachine as well as selectively disconnect the electric machine from thetransmission, during certain operating conditions. In this way, the PTOis able to operate over a wider range of operating conditions.

FIG. 1 depicts a vehicle 100 with an electric driveline system 102. Assuch, the vehicle 100 may be an electric vehicle (EV), such as a batteryelectric vehicle (BEV). All-electric vehicles may specifically be useddue to their reduced complexity and therefore reduced points ofpotential component degradation. However, hybrid electric vehicle (HEV)embodiments may be employed where the vehicle includes an internalcombustion engine (ICE).

The electric driveline system 102 includes a transmission 104 that isrotationally coupled to a first electric machine 106 and a secondelectric machine 108. Each of the electric machines 106, 108 may includeconventional components such as a rotor and a stator thatelectromagnetically interact during operation to generate motive power.Furthermore, the electric machines may be motor-generators which alsogenerate electrical energy during regeneration operation. Further, theelectric machines may have similar designs and sizes, in one example. Inthis way, manufacturing efficiency may be increased. However, theelectric machines may have differing sizes and/or component designs, inalternate examples.

Further, the electric machines 106, 108 may be multi-phase electricmachines that are supplied with electrical energy through the use of afirst inverter 110 and a second inverter 112. These inverters and theother inverters described herein are designed to convert direct current(DC) to alternating current (AC) and vice versa. As such, the electricmachines 106, 108 as well as the other electric machines may be ACmachines. For instance, the electric machines 106, 108 and the inverters110, 112 may be three-phase devices, in one use-case example. However,motors and inverters designed to operate using more than three phaseshave been envisioned. The electrical connections between the inverters110, 112 and the electric machines 106, 108 is indicated via lines 114,116 (e.g., multi-phase wires), respectively.

The inverters 110, 112 may receive DC power from at least one electricalenergy source 118 (e.g., an energy storage device such a tractionbattery, a capacitor, combinations thereof, and the like, and/or analternator). Arrows 120 indicate the flow of electrical energy from theenergy source 118 to the electric machine 106, 108. Alternatively, eachinverter may draw power from at least one distinct energy source. Whenboth the inverters are coupled to one energy source, the inverters mayoperate at a similar voltage. Alternatively, if both inverters arecoupled to distinct electrical energy sources, they may operate atdifferent voltages, in some examples.

The system 102 further includes a PTO assembly 119. The PTO assembly 119includes a PTO 128 (e.g., a mechanical or hydraulic PTO unit) and mayalso include a PTO gearset 130. The PTO gearset 130 may include a gear137 and a gear 131 coupled to the output shaft 121 such that the gear131 and the output shaft 121 jointly rotate. A bearing 143 may serve asan interface between the gear 137 and an input shaft 129 of the PTO 128.Thus, the gear 137 and the input shaft 129 may independently rotate,under some conditions, elaborated upon herein. One or more auxiliarydevices 115 may be driven by the PTO 128 as denoted via line 117. Theseauxiliary devices may include a steering pump, a pump for workinghydraulic devices, an air conditioning pump, and the like.

The PTO assembly 119 may utilize clutches (e.g., friction clutches,synchronizers, dog clutches, combinations thereof, and the like) toselectively provide mechanical power to the PTO 128, as will be expandedupon herein. As such, the PTO assembly 119 may be designed tomechanically couple and decouple the PTO 128 from the electric machine106. Although the PTO 128 is designed to selectively rotationally coupleto the first electric machine 106, the second electric machine 108 may,additionally or alternatively, have a PTO and an associated gear andclutch assembly coupled thereto. However, when the system includes twoPTOs coupled to the different electric machines, one of the PTOs may bedisconnected during reverse drive operation.

In some examples, the output shaft 121 of the first electric machine 106may have a gear 131 fixedly coupled thereon. The gear 131 may be coupledto a gear 137 of the PTO gearset 130. The gears described herein includeteeth, and mechanical attachment between the gears involves meshing ofthe teeth. The gear 137 may be disposed about, and selectively coupledto, an input shaft 129 of the PTO 128. For instance, a bearing 143 maybe used to attach the gear 137 to the PTO input shaft 129 such that thegear 137 independently rotates in relation to the PTO input shaft 129during certain operating conditions. Further the gears 131, 137 includedin the PTO gearset 130 may have a gear ratio that is selected to providerotational input to the PTO within a desired torque range.

The PTO assembly 119 includes a first clutch 141. The first clutch 141is specifically illustrated as a synchronizer, although other types ofclutches, such as friction clutches, may be additionally oralternatively used for selectively coupling the PTO gearset 130 to theshaft 129, in other examples. Further, the clutch 141 may be designed toselectively couple the gear 137 for rotation with the PTO input shaft129, by coupling the gear 137 with a shaft interface 139 of the inputshaft 129. In this way, when the clutch 141 is engaged, mechanical powerfrom the electric machine 106 may be transferred to the input shaft 129of the PTO 128 via gears 131 and 137. Conversely, when the clutch 141 isnot engaged, mechanical power from the electric machine 106 may nottravel through the PTO gearset 130, whereby the gear 137 of the PTOgearset is not able to transfer mechanical power to the input shaft 129of the PTO. In other words, the clutch 141 allows the PTO 128 to beselectively connected and disconnected from the first electric machine106 in different operating modes. Further, a shift fork or othersuitable actuator, as schematically illustrated at 113, may be used toengage and disengage the clutch 141.

The output shafts 121, 122 of the electric machines 106, 108 may havegears 124, 126 which reside thereon, respectively. In some examples, thegear 124 may be rotatably coupled to the output shaft 121. To rotatablyattach the gear 124 to the shaft 121, a bearing 123 (e.g., a rollerbearing such as needle roller bearing, a ball bearing, and the like) maybe used. A bearing as described herein may include inner races, outerraces, and roller elements (e.g., balls, cylindrical rollers, taperedcylindrical rollers, and the like). This rotatable attachment betweenthe gear 124 and the output shaft 121 allows the first electric machine106 to be selectively rotationally decoupled from the transmission 104.

To accomplish the selective decoupling of the first electric machine 106from the transmission 104, a second clutch 135 may be included in thePTO assembly 119, in some examples. Further, the second clutch 135 maybe included in a clutch assembly 127. The clutch assembly 127 may bepositioned coaxial to the output shaft 121 and is designed toselectively couple the gear 124 for rotation with the output shaft 121.The clutch assembly 127 may further include a synchronizer 133positioned in series with a friction clutch 135. More specifically, thesynchronizer 133 and the friction clutch 135 may be coaxially arranged.A friction clutch, as described herein, may include two sets of platesdesigned to frictionally engage and disengage one another while theclutch is opened and closed. As such, the amount of torque transferredthrough the clutch may be modulated depending on the degree of frictionplate engagement. Thus, the friction clutches described herein may beoperated with varying amounts of engagement (e.g., continuously adjustedthrough the clutch's range of engagement). Further, the frictionclutches described herein may be wet friction clutches through whichlubricant is routed to increase clutch longevity. However, dry frictionclutches may be used in alternate examples. The friction clutch 135 andother friction clutches described herein may be adjusted via hydraulic,pneumatic, and/or electro-mechanical actuators. For instance,hydraulically operated pistons may be used to induce clutch engagementof the friction clutches. However, solenoids may be used forelectro-mechanical clutch actuation, in other examples.

The friction clutch 135 may include a drum 145 coupled to the outputshaft 121 and carrying a set of the friction plates, and a clutchcomponent 125 (e.g., clutch hub) that carries a set of separator plates.Further, the synchronizer 133 may be designed to selectively couple thegear 124 for rotation with the clutch component 125 of the frictionclutch 135. Thus, when the friction clutch 135 is engaged (e.g., in aclosed position), the synchronizer 133 may engage an interface of thegear 124 so that the gear 124 is coupled for rotation with the outputshaft 121 of the electric machine 106.

The synchronizer 133 is designed to synchronize the speed of the clutchcomponent 125 of the friction clutch 135 (e.g., as effected by theoutput shaft 121 and the degree of engagement of the friction plates inthe clutch 135) and the gear 124. For instance, the synchronizer 160 mayinclude a sleeve with splines, ramped teeth, and the like designed toengage an interface of the gear 124 in order to achieve theaforementioned functionality. Further, a shift fork or other suitableactuator, as schematically illustrated at 166, may be used to engage anddisengage the synchronizer 133. In this way, when the friction clutch135 and the synchronizer 133 of the clutch assembly 127 engage the gear124, mechanical power output from the electric machine 106 (via theoutput shaft 121) may be transferred into the transmission 104, as willbe described herein. Conversely, the electric machine 106 may bedecoupled from the transmission 104 when the clutch assembly 127 isdisengaged from the gear 124.

It will be understood that, in different examples, the PTO gearset 130and the output shaft 121 of the electric machine 106 may utilizedifferent configurations of clutches and/or synchronizer mechanisms forachieving the aforementioned functionalities. For instance, in somecases, the clutch assembly 127 may include a single wet friction clutchwithout the synchronizer 133 and/or the clutch 141 may be a wet frictionclutch arranged for coupling the gear 137 of the PTO gearset 130 to theinput shaft 129 of the PTO 128. However, other clutch arrangements(e.g., dry friction clutches, dog clutches, etc.) have beencontemplated, in different examples. Further, in different embodiments,the clutch 141 or the clutch assembly 127 may be omitted from thetransmission 104. In these embodiments, the transmission's packagingefficiency may be increased at the expense of reduced functionality.

The gears 124, 126 are each coupled to (e.g., in meshing engagementwith) a gear 134 of a planetary gearset 136 in the transmission 104. Theplanetary gearset 136 may include a shaft 140 which connects the gear134 to a sun gear 142. The gears 124, 126 may specifically be positionedon different sides 144, 146 of the transmission 104 to enhance packagingand provide a more balanced weight distribution in the electricdriveline system 102, if wanted. More generally, the rotational axes ofthe gears 124 and 126 as well as the electric machines 106 and 108 maybe parallel to one another.

A friction clutch 148 is coupled to the shaft 140 and designed toselectively rotationally couple the shaft to an output shaft 150. Insome examples, the friction clutch 148 may be substantially similar tothe friction clutch 135 as described above, and may therefore be a wetfriction clutch. The sun gear 142 in the planetary gearset 136 may becoupled to the shaft 140. Further, planet gears 152, in the planetarygearset 136, may be coupled to the sun gear 142. Further, the planetgears 152 may be mechanically coupled to a ring gear 154 in theplanetary gearset 136.

A shaft 156 may extend from the ring gear 154 and have a second frictionclutch assembly 158 residing thereon. The second friction clutchassembly 158 may include a synchronizer 160 arranged in series with afriction clutch 162. Placing the synchronizer 160 in series with thefriction clutch 162 enables the transmission's efficiency to beincreased when operating in the second gear. Again, the synchronizer160, as well as the other synchronizers described herein, may be similarto the synchronizer 133 and actuated accordingly. To elaborate, thesynchronizer 160 permits a portion of the shaft 164 to be disconnectedfrom the clutch 162 and freely rotate while the system operates in thesecond gear. As such, the plates in the clutch 162 may not rotate whenthe synchronizer is disengaged. Conversely, when the synchronizer 160 isengaged, the shaft 164 and the shaft 156 of the ring gear 154 rotate inunison. The synchronizer 160 is designed to synchronize the speed of theshaft 156 and a shaft 164 coupled to the friction clutch 162, andmechanically lock rotation of the shafts 156, 164, when engaged. Toincrease system compactness, the friction clutches 148, 162 as well asthe output shaft 150 may be coaxially arranged. To permit this coaxialarrangement, the sun gear 142 may include an opening 168 through whichthe output shaft extends.

The friction clutch 162 is designed to ground the ring gear 154. Toaccomplish the ring gear grounding, the friction clutch 162 may includea housing with a portion of the friction plates coupled thereto andfixedly attached to a stationary component, such as the transmission'shousing. A bearing 170 may be positioned between the shaft 156 and theoutput shaft 150 to enable these shafts to independently rotate, duringcertain conditions.

The output shaft 150 includes output interfaces 172, 174 (e.g., yokes,splines, combinations thereof, or other suitable mechanical interfaces)designed to attach to axles (e.g., front or rear axles) via shafts,joints (e.g., U-joints), chains, combinations thereof, and the like.

Disconnect clutches 176, 178 may be provided for each of the outputinterfaces 172, 174. As such, the disconnect clutches 176, 178 may bedesigned to mechanically couple and decouple the output shaft 150 fromthe output interfaces 172, 174. In this way, the transmission'scapabilities may be further expanded to enable single and multi-axleoperation. For instance, four-wheel drive may be engaged when additionaltraction is desired and two-wheel drive may be engaged when theadditional traction is not desired to reduce driveline losses and tirewear. In this way, the handling performance of the vehicle is enhanced.The disconnect clutches 176, 178 may be dog clutches, synchronizers,friction clutches, combinations thereof, or other suitable clutches. Dogclutches and/or synchronizers may be specifically used as axledisconnect devices, in some examples, to reduce losses when the clutchesare disengaged, when compared to friction clutches.

The planet gears 152 rotate on a carrier 179 of the planetary gearset136. The carrier 179 is rotationally coupled to the output shaft 150.The planetary gearset 136 may be a simple planetary gearset that solelyincludes the sun gear 142, ring gear 154, planet gears 152, and carrier179. By using a simple planetary assembly, transmission compactness maybe increased when compared to more complex planetary assemblies such asmulti-stage planetary assemblies, Ravigneaux planetary assemblies, andthe like. Consequently, the driveline system may pose less spaceconstraints on other vehicle components, thereby permitting the system'sapplicability to be expanded. Further, losses in the transmission may bedecreased when a simple planetary gearset is used as opposed to morecomplex gear arrangements.

Depending on the gear ratio of the transmission, mechanical power maytravel through the carrier 179 to the output shaft 150 or from the sungear 142 to the output shaft. Mechanical power paths through thetransmission in the different gears and shifting operation (e.g.,powershifting operation) between the operating gears are discussed ingreater detail herein with regard to FIGS. 2A-2D.

A third electric machine 180 and inverter 182 may be provided in thesystem 102. The third electric machine 180 is designed to drive atransmission pump 184 which generates the flow of a fluid (e.g., alubricant such as oil) through the transmission 104. It will beunderstood that lubricant as described herein is a fluid such as oilthat may be used for lubricating components as well as for componentactuation and/or cooling. Furthermore, a valve 186 is coupled to anoutput of the pump 184 and regulates the flowrate of lubricant throughthe transmission 104. The valve 186 may be in fluidic communication withcomponents 185 (schematically depicted in FIG. 1 ) in the transmission104 that receive lubricant. The lubricant may be routed to the desiredcomponents via lubricant conduits, jets, additional valves, manifolds,combinations thereof, and the like. Further, the components 185 mayinclude gears, clutches, hydraulic pistons for clutch actuation, and thelike.

Once the lubricant is routed from the valve 186 to the lubricatedcomponents, the lubricant returns to a sump 187. Additionally, the sump187 may be located in a transmission housing and profiled to gatherlubricant from the lubricated components in the transmission. The pump184 may receive lubricant from the sump 187 via pick-up conduits 188.Conversely, the pump outlets 189 deliver lubricant to the valve 186. Itwill be understood that the pump 184, the valve 186, and the sump 187are included in a lubrication system 190. The lubrication system 190 mayfurther include conduits for routing the lubricant to targetedcomponents in the transmission such as the planetary gearset, clutches,and the like. The pump is illustrated in FIG. 1 as a double pump withtwo pump modules 191, but other pump designs have been contemplated.

Further, by using a separate electric machine to drive the transmissionpump 184, the electric machine's speed and therefore pump speed may beadjusted to track with the lubricant demands in the transmission. Forinstance, the pump speed may be increased during shifting transients andthen decreased while the transmission is sustained in one of the twodiscrete operating gears. This reduces hydraulic losses and allows thehydraulic system to be downsized, if desired.

The third electric machine 180 and the inverter 182 may be operated witha lower voltage current than the first and second electric machines 106,108 and corresponding inverters. For instance, the lower voltage may bein the following range: 12 Volts (V)-144V and the higher voltage may bein the following range: 350V-800V, in one use-case example. However,other higher and lower voltage values may be used, in other examples. Inthis way, the transmission's efficiency may be increased. However, inother examples the first electric machine 106, the second electricmachine 108, and the third electric machine 180 may be operated at asimilar voltage (e.g., a higher voltage within the range of 350V-800V ora lower voltage within the range of 12V-144V, in one use-case example).

The vehicle 100 further includes a control system 192 with a controller193 as shown in FIG. 1 . The controller 193 may include a microcomputerwith components such as a processor 194 (e.g., a microprocessor unit),input/output ports, an electronic storage medium 195 for executableprograms and calibration values (e.g., a read-only memory chip, randomaccess memory, keep alive memory, a data bus, and the like). The storagemedium may be programmed with computer readable data representinginstructions executable by a processor for performing the methods andcontrol techniques described herein as well as other variants that areanticipated but not specifically listed.

The controller 193 may receive various signals from sensors 196 coupledto various regions of the vehicle 100 and specifically the transmission104. For example, the sensors 196 may include a pedal position sensordesigned to detect a depression of an operator-actuated pedal such as anaccelerator pedal and/or a brake pedal, a speed sensor at thetransmission output shaft, energy storage device state of charge (SOC)sensor, clutch position sensors, etc. Motor speed may be ascertainedfrom the amount of power sent from the inverter to the electric machine.An input device 197 (e.g., accelerator pedal, brake pedal, drive modeselector, PTO mode selector, two wheel and four-wheel drive selector,combinations thereof, and the like) may further provide input signalsindicative of an operator's intent for vehicle control. For instance,buttons, switches, or a touch interface may be included in the vehicleto enable the operator to toggle between a two-wheel drive mode and afour-wheel drive mode and/or engage and disengage the PTO from the firstelectric machine. However, in other examples, automated controlstrategies may be used to connect and disconnect the PTO.

Upon receiving the signals from the various sensors 196 of FIG. 1 , thecontroller 193 processes the received signals, and employs variousactuators 198 of vehicle components to adjust the components based onthe received signals and instructions stored on the memory of controller193. For example, the controller 193 may receive an accelerator pedalsignal indicative of an operator's request for increased vehicleacceleration. In response, the controller 193 may command operation ofthe inverters to adjust electric machine power output and increase thepower delivered from the machines to the transmission 104. Thecontroller 193 may, during certain operating conditions, be designed tosend commands to the clutches 141, 135, 148, 162, and/or synchronizer133 to engage and disengage the clutches or synchronizer. For instance,a control command may be sent to a clutch assembly and in response toreceiving the command, an actuator in the clutch assembly may adjust theclutch based on the command for clutch engagement or disengagement. Theother controllable components in the vehicle may function in a similarmanner with regard to sensor signals, control commands, and actuatoradjustment, for example.

The controller 193 may be designed to control the clutches 148, 162 tosynchronously shift between two of the transmission's operating gears.Further, the controller 193 may be designed to operate the clutches 135,141, and/or the synchronizer 133 to selectively connect the PTO 128and/or the transmission 104 from the first electric machine 106.

An axis system 199 is provided in FIG. 1 , as well as FIGS. 2A-2D, forreference. The z-axis may be a vertical axis (e.g., parallel to agravitational axis), the x-axis may be a lateral axis (e.g., horizontalaxis), and/or the y-axis may be a longitudinal axis. However, alternateorientations of the axes may be used, in other examples.

The transmission 104 has two clutches that enable it to function as atwo-speed transmission. However, in other embodiments, additionalclutches may be added to the transmission to enable it to be operated ina greater number of gears. As such, the transmission may have three ormore speeds, in other embodiments.

FIGS. 2A-2D depict power paths through the transmission 104 in fourdifferent operating modes. In the operating modes, depicted in FIGS. 2Aand 2B, power bypasses the PTO 128. However, in the operating modes,depicted in FIGS. 2C and 2D, power is provided to the PTO 128. Thecomponents in the electric drivelines system 102, the transmission 104,etc. shown in FIGS. 2A-2D and previously described with regard to FIG. 1are similarly numbered and redundant description is omitted for brevity.

FIGS. 2A and 2B show the power paths through the transmission 104 in theelectric driveline system 102 in a first gear mode and a second gearmode, respectively, where the PTO 128 is disconnected from the firstelectric machine 106. It will be understood that these power paths maycorrespond to both forward and reverse drive modes. Further, theelectric machines may generate rotational output in opposite directionsin the forward and reverse drive modes. In other words, in a forwarddrive mode, the first electric machine may rotate the output shaft 121in a first direction and in a reverse drive mode, it may rotate theoutput shaft in the opposite direction. Thus, the power paths shown inFIGS. 2A and 2B generally correspond to drive mode operation.

The transmission's gear ratio in the first gear mode is higher than thegear ratio in the second gear mode. Thus, the first gear may be usedduring launch and subsequent acceleration while the second gear may beused for cruising operation, for instance. Further, as shown in FIGS. 2Aand 2B, the disconnect clutches 176, 178 are engaged and thereforepermit power to be transferred from the output shaft 150 both outputinterfaces 172, 174 and drive axles, correspondingly. However, one ofdisconnect clutches may be disengaged while the transmission isoperating in the first gear and the second gear, when additionaltraction is not desired. For example, one of the disconnect clutches maybe disengaged and vehicle correspondingly operates in a two-wheel drivemode when a vehicle operator requests said mode or when it is determinedthat the vehicle is not operating under low traction conditions.

Turning specifically to FIG. 2A, while the transmission 104 is operatingin the first gear mode, the ring gear 154 is held stationary by thefriction clutch 162 and the clutch 148 is disengaged. Further, theclutch 141 is disengaged so that the PTO gearset 130 is disconnectedfrom the electric machine 106, and the clutch assembly 127 that includesthe friction clutch 135 and the synchronizer 133 is engaged to couplethe gear 124 for rotation with the output shaft 121 of the electricmachine 106. The mechanical power path in the first gear mode (denotedvia arrows 250) unfolds as follows: mechanical power moves from thefirst and second electric machines 106, 108 to the gear 124, 126,respectively, from the gears 124, 126 to the gear 134, from the gear 134to the sun gear 142, from the sun gear to the planet gears 152, from theplanet gears to the carrier 179, and from the carrier to the outputshaft 150.

While the transmission 104 is operating in the second gear mode, asshown in FIG. 2B, the clutch 148 is engaged to permit mechanical powertransfer between the gear 134 and the output shaft 150 and the clutch162 is disengaged. Again, the clutch 141 is disengaged so that the PTOgearset 130 is disconnected from the electric machine 106, and theclutch assembly 127 is engaged to couple the gear 124 for rotation withthe output shaft 121 of the electric machine 106. In the second gearmode, the mechanical power path (denoted via arrows 260) unfolds asfollows: mechanical power moves from the first and second electricmachines 106, 108 to the gears 124, 126, respectively, from the gears124, 126 to the gear 134, from the gear 134 to the clutch 148, and fromthe clutch 148 to the output shaft 150.

FIG. 2C shows the transmission 104 operating in a first gear mode inwhich the first electric machine 106 transfers power to both thetransmission 104 and the PTO 128. Thus, in the first gear modeillustrated in FIG. 2C, the ring gear 154 is held stationary by thefriction clutch 162 and the clutch 148 is disengaged. Further, theclutch assembly 127 is engaged (e.g., the clutch 135 and thesynchronizer 133 are engaged) to enable mechanical power to betransferred from the output shaft 121 to the gear 124, and the clutch141 is engaged enable power to be transferred from the gear 137 of thePTO gearset to the PTO input shaft 129. In this way, the first electricmachine 106 is able to provide power to both the transmission 104 andthe PTO 128.

In FIG. 2C the mechanical power path (denoted via arrows 270 and 272)unfolds as follows: mechanical power moves from the first and secondelectric machines 106, 108 to the gear 124, 126, respectively, from thegears 124, 126 to the gear 134, from the gear 134 to the sun gear 142,from the sun gear to the planet gears 152, from the planet gears to thecarrier 179, and from the carrier to the output shaft 150. Additionally,a branch of the mechanical power path (denoted by arrows 272) flows fromthe electric machine 106 to the gear 131, from the gear 131 to the gear137 of the PTO gearset 130, and from the gear 137 through the PTO inputshaft 129 to the PTO 128. From the PTO 128 mechanical power may flow tothe auxiliary device(s) 115. Thus, the operating mode, depicted in FIG.2C, may be implemented to jointly power the PTO while executing forwarddrive operation. However, it will be understood that the first electricmachine 106 is capable of transferring mechanical power to the PTO 128across a wide speed range (e.g., the entire speed range) of the electricmachine, as a result of the to the configuration of the clutch 141 andthe clutch assembly 127 with the PTO gearset 130.

While the transmission 104 is operating in the mode illustrated FIG. 2D,the transmission 104 is again in the first gear ratio and operated toprovide power to the PTO. However, unlike in the mode depicted in FIG.2C, the first electric machine 106 is disconnected from the transmissionin the mode depicted in FIG. 2D and the second electric machine 108 maybe spun in a reverse such that the transmission 104 propels the vehiclebackwards. Thus, in this mode, the clutch assembly 127 is disengaged,and the clutch 141 is engaged. Further, the ring gear 154 is heldstationary by the friction clutch 162 and the clutch 148 is disengaged.The mechanical power path in the operating mode of FIG. 2D includes twopower paths: a traction power path (denoted by arrows 280) and a PTOpower path (denoted by arrows 282). The traction power path 280 unfoldsas follows: mechanical power (e.g., produced via torque from the secondelectric machine 108 that has a reverse rotational direction) moves fromthe second electric machine 108 to the gear 126, from the gear 126 tothe gear 134, from the gear 134 to the sun gear 142, from the sun gearto the planet gears 152, from the planet gears to the carrier 179, andfrom the carrier to the output shaft 150. The PTO power path 282 unfoldsas follows: mechanical power moves from the electric machine 106 throughthe output shaft 121 to the gear 131, from the gear 131 to the gear 137,from the gear 137 through the PTO input shaft 129 to the PTO 128. Fromthe PTO 128 mechanical power may flow to the auxiliary device(s) 115. Inthis way, the second electric machine 108 may be operated to providereverse drive traction while the first electric machine 106 providespower to the PTO 128, in some examples, or while the vehicle is at astandstill (e.g., when electric machine 108 is not providing power tothe transmission), in other examples.

FIG. 2E shows a chart 290 that correlates the configurations of thefriction clutches 135, 148, 162 and the synchronizers 133, 141, 160 tothe first and second gears while the system is operated in a forwarddrive mode with the PTO disconnected. In FIG. 2E as well as FIGS. 2F and2G, an “X” denotes clutch engagement and a blank field converselydenotes clutch disengagement. Specifically, in the first gear mode, thefriction clutch 148 is disengaged and the friction clutch 162 as well asthe synchronizer 160 are engaged. Conversely, in the second gear mode,the friction clutch 148 is engaged and the friction clutch 162 as wellas the synchronizer 160 are disengaged. In both the first and secondgear modes, the synchronizer 141 is disengaged and the clutch 135 andsynchronizer 133 are engaged, thereby disconnecting the first electricmachine from the PTO and connecting the first electric machine and thetransmission. To powershift between the first gear and the second gear,the clutch 148 may be engaged while the clutch 162 is disengaged.Subsequently to disengagement of the clutch 162, the synchronizer 160may be disengaged. Conversely, to shift from the second gear back to thefirst gear, the synchronizer 160 may first be engaged and subsequentlythe clutch 162 may be engaged while the clutch 148 is disengaged. Itwill be understood that the synchronizer may be omitted from the system,in some examples. When powershifting is implemented in the transmission,power interruptions during shifting may be substantially avoided,thereby enhancing shifting performance.

FIG. 2F shows a chart 292 that correlates the configurations of thefriction clutches 135, 148, 162 and the synchronizers 133, 141, 160 tothe first and second gears while the system is operated in a forwarddrive mode with the PTO connected to the first electric machine. Theconfiguration of the clutches 148, 162 and synchronizer 160 areidentical to FIG. 2E and repeated description is therefore omitted forbrevity. However, each of the synchronizers 133, 141 and the clutch 135are engaged such that power is transferred from the first electricmachine to both the transmission and the PTO in both the first andsecond gears. In this way, power may be transferred to the PTO across awide vehicle speed range. As a result, the vehicle PTO capabilities areexpanded, thereby increasing customer appeal.

FIG. 2G shows a chart 294 that correlates the configurations of thefriction clutches 135, 148, 162 and the synchronizers 133, 141, 160 tothe first and second gears while the system is operated in a reversedrive mode with the PTO connected to the first electric machine. It willbe appreciated, that in the reverse drive mode the second electricmachine is spun in a reverse rotational direction to propel the vehiclein reverse. The configuration of the clutches 148, 162 and synchronizer160 are identical to FIG. 2F and repeated description is thereforeomitted for concision. However, the synchronizer 141 is engaged and thesynchronizer 133 and the clutch 135 are disengaged such that power istransferred from the first electric machine to the PTO in both the firstand second gears while power transfer from the first electric machine tothe transmission is inhibited. In this way, the second electric machineis able to provide reverse drive rotational input to the transmissionwithout interfering with PTO operation. Consequently, the system's PTOcapabilities are even further expanded.

FIG. 3A-3C show another example of a vehicle 300 with an electricdriveline system. The boundary of the electric driveline system isdenoted via dashed lines 302. However, it will be appreciated that thesystem may include a different grouping of components, in otherexamples. The electric driveline system 302 includes a transmission 304.The electric driveline system 302 with the transmission 304 shown inFIGS. 3A-3C may share common features with the electric driveline system102 and the transmission 104 shown in FIGS. 1-2D. Redundant descriptionis therefore omitted. FIGS. 3A-3C specifically illustrate themechanical, coolant, and electrical connections, respectively, betweencomponents in the electric driveline system 302 as well as other vehiclecomponents. Although the mechanical, coolant, and electrical connectionsare illustrated in separate figures for clarity, it will be understoodthat these connections may all be present in the electric drivelinesystem.

The driveline system 302, shown in FIGS. 3A-3C, include a first electricmachine 306, a second electric machine 308, and a third electric machine310. The electric driveline system 302 further includes a first inverter312, a second inverter 314, and a third inverter 316 that are associatedwith the first electric machine 306, the second electric machine 308,and the third electric machine 310, respectively. The vehicle 300further includes a pump 319 that is designed to circulate lubricant(e.g., oil) in the transmission 304. A valve 321 coupled to thetransmission 304 may be used to regulate lubricant flow from the pump319 to the transmission.

The vehicle 300 further includes a first axle 320 (e.g., a front axle)and a second axle 322 (e.g., rear axle). The vehicle 300 may furtherinclude auxiliary devices 324, such as a steering pump, an airconditioning pump, a hydraulic pump for working functions, and the like.Still further, the vehicle may include a coolant circuit 326, a lowervoltage power source 328 (e.g., a battery, a capacitor, combinationsthereof, and the like), and a higher voltage power source 330 (e.g., abattery, a capacitor, combinations thereof, and the like). The drivelinesystem 302 may include a DCU 332 and the vehicle 300 may include a VCU334. However, other control unit arrangements have been contemplated,such as a common control unit which is used to adjust operation of boththe driveline system 302 and components in the vehicle 300. Each of thecontrol units may include any know data storage mediums (e.g., randomaccess memory (RAM), read only memory (ROM), keep alive memory,combinations thereof, and the like) and a processor (e.g.,micro-processor unit) designed to execute instructions stored in thedata storage mediums. As such, the DCU 332 and/or the VCU 334 mayperform the control methods, techniques, schemes, etc. described hereinsuch as the method shown in FIG. 4 . Further the DCU may be designed tocoordinate operation of the inverters 312, 314, and 316 to increase thesystem's efficiency. For instance, the DCU may be operated to balancepower between the inverter 312 and 314 to increase the drivelinesystem's efficiency. Specifically, in one example, the DCU may operatethe inverter 312 and 314 to reduce torque generated by one of theelectric machines and increase torque generated by the other electricmachine such that they operate in a target efficiency point or range.Additionally, the DCU may be operated to control the inverter 316 toenable a desired lubricant flow to be achieved. The DCU may further bedesigned to implement fault reactions and diagnostics. For example, theDCU may implement a limp home mode when minor component degradation isdetected, such as a degradation of a speed sensor. Further, the DCU mayshutdown if the controller area network (CAN) is degraded, in somescenarios.

A heat exchanger 336 may further be coupled to (e.g., directly coupledto or incorporated into) the transmission 304. In other examples, theheat exchanger 336 may be coupled to a vehicle frame 337. The heatexchanger 336 may include components for transferring thermal energybetween a coolant circuit and an oil circuit, such as adjacent coolantand oil passages, a housing, and the like. In this way, heat may beefficiently removed from the transmission's lubrication circuit. In oneexample, the heat exchanger 336, such as a liquid-liquid cooler, may bebolted or otherwise mechanically attached to the transmission housing.In another example, the heat exchanger 336 may be formed by integratingcoolant passages into the sump housing.

Electric PTOs 338, 340 may further be included in the vehicle 300. Theelectric PTO 338 may include a higher voltage motor and an inverter 341coupled to auxiliary devices 342 (e.g., a steering pump, a pump forworking hydraulic devices, an air conditioning pump, and the like). Theelectric PTO 340 may include a lower voltage motor and an inverter 343coupled to auxiliary devices 344. Providing electric PTOs in the vehicleexpands the vehicle's capabilities and adaptability. Consequently, thedriveline system may be used in a wider variety of vehicle platforms.Furthermore, by using electric PTOs that operate with differentvoltages, the motors in the PTOs may be granularly tuned to meet thedemands of the specific auxiliary devices to which they are attached, ifwanted. However, in other examples, the electric PTO may be operatedusing a similar voltage.

The driveline system 302 may further include a first axle disconnectclutch 345 and a second axle disconnect clutch 346. Each of thedisconnect clutches may be friction clutches, dog clutches, or othersuitable clutches that are designed to rotationally couple and decouplethe transmission output interfaces from the corresponding axle. A PTO347 may further be coupled to the transmission 304 and the auxiliarydevices 324.

FIG. 3A maps the mechanical connections between the components in thedriveline system 302 as well as the vehicle 300. These mechanicalconnections are denoted via lines 350. The mechanical connections may beformed via shafts, joints, belts, chains, combinations thereof, and thelike. As shown, the first electric machine 306 and the second electricmachine 308 are rotationally coupled to the transmission 304. Providingtwo electric machines mechanically coupled to the transmission maypermit driveline efficiency to be increased. Further, the likelihood ofthe driveline system becoming inoperable due to motor degradation isreduced when there is electric machine redundancy in the drivelinesystem.

The transmission 304 is also rotationally coupled to the first axle 320and the second axle 322, and the disconnect clutches 345, 346 may permitthe axles to be connected and disconnected from the transmission 304according to operator input and/or vehicle operating conditions, forinstance.

The third electric machine 310 may be rotationally coupled to the pump319 and the pump may be in fluidic communication with the transmission304 via the valve 321. The third electric machine 310 may be operatedindependently from the first and second electric machines 306, 308. Toelaborate, the third electric machine 310 may be adjusted to more aptlytrack with the lubricant demands of the transmission. In this way, thesystem's efficiency can be increased without impacting transmissionlubrication operation, if wanted.

The PTO 347 is mechanically coupled to the auxiliary devices 324.Further, the electric PTOs 338, 340 are mechanically coupled to theauxiliary devices 342, 344, respectively. In this way, the system's PTOcapabilities may be expanded to meet a variety of auxiliary devicedemands across a wide breadth of vehicle platforms. The system'scustomer appeal is consequently increased.

FIG. 3B shows the coolant connections, denoted via lines 352, in acooling assembly 354 of the electric driveline system 302. The coolantconnections may be established via conduits, ducts, and the like whichare routed (e.g., internally and/or externally routed) through varioussystem components. The coolant may include water and/or glycol. Thecooling assembly 354 may include the coolant circuit 326 which may havea coolant pump and a heat exchanger. As shown, coolant may be routed tothe heat exchanger 336, the first electric machine 306, the secondelectric machine 308, the first inverter 312, and the second electricmachine 308 in parallel. Additionally or alternatively, the coolant maybe routed to one or more of the following components in series: the heatexchanger 336, the first electric machine 306, the second electricmachine 308, the first inverter 312, and the second electric machine308. In this way, the electric machines, inverters, and transmissionlubricant may be efficiently cooled. The heat exchanger 336 is designedto transfer heat from lubricant (e.g., oil) routed through thetransmission to coolant in the cooling assembly 354. Providing the heatexchanger with an oil to coolant heat transfer functionality permits aliquid to air heat exchanger, such as a radiator, to be omitted from thesystem, if wanted. The system's size, complexity, and/or manufacturingcosts may be reduced, as a result.

Alternatively, the first and/or second electric machines 306, 308 aswell as the first and/or second inverters 312, 314 may be oil cooled. Insuch an example, the heat exchanger 336 may be omitted from the system.

FIG. 3C shows electrical and data connections in the vehicle 300 and theelectric driveline system 302. The electrical connections arespecifically divided into higher voltage connections (denoted by thickerlines 356) and lower voltage connections (denoted by thinner lines 358).Data connections are denoted via dashed lines 360. The higher voltageconnections emanate from the higher voltage power source 330 and thelower voltage connections emanate from the lower voltage power source328. In one use-case example, the lower voltage may in the range between12V and 144V and the higher voltage may be in the range between 350V and800V.

The higher voltage power source 330 may be electrically coupled to thefirst inverter 312 and the second inverter 314. Likewise, higher voltageelectrical connections may be established between the first and secondelectric machines 306, 308 and the first and second inverters 312, 314.A higher voltage connection may additionally be established between theelectric PTO 338 and the driveline system 302.

The lower voltage power source 328 may be electrically coupled to thefirst inverter 312, the second inverter 314, the third inverter 316,and/or the DCU 332. A lower voltage connection may additionally beestablished between the third inverter 316 and the third electricmachine 310 as well as the electric PTO 340 and the driveline system302. Further, a lower voltage connection may be established between theDCU 332 and the valve 321.

Data connections may be established between the VCU 334 and the DCU 332.For instance, operating condition data such as vehicle speed, pedalposition (e.g., brake pedal position and/or accelerator pedal position),drive mode selector positon, and the like may be transferred from theVCU to the DCU. Conversely, operating condition data such as electricmachine speed, electric machine temperature, power source SOC, clutchposition, transmission temperature, and the like may be transferred fromthe DCU to the VCU. In this way, data may be shared between the DCU andthe VCU to enhance control routines at each control unit. A dataconnection may also be established between the DCU 332 and the firstinverter 312, the second inverter 314, and/or the third inverter 316.Further, data may be transferred from the electric PTOs 338 and 340 tothe driveline system 302.

FIG. 4 shows a method 400 for operation of an electric driveline system.The method 400 may be carried out via the electric driveline systems 102and/or 302, discussed above with regard to FIGS. 1-3C, in one example.However, in other examples, the method 400 may be implemented by othersuitable electric driveline systems. Instructions for carrying outmethod 400 may be executed by a controller, such as the controller 193in FIG. 1 or the DCU 332 and/or the VCU 334 in FIGS. 3A-3C, by executinginstructions stored in a memory of the controller and in conjunctionwith signals received from sensors at the controller. The controller mayemploy actuators in different system components to implement the methodsteps described below.

At 402, the method includes determining operating conditions. Theoperating conditions may include speeds of the electric machines,transmission output shaft speed, vehicle speed, clutch positon, pedalposition, transmission load, current PTO power demand, and the like.These conditions may be determined using sensors and/or modelingalgorithms.

At 404, the method judges if the PTO (e.g., PTO 128, shown in FIG. 1 )should be connected to the transmission to receive power therefrom. ThePTO connection judgment may be carried out based on an operator demand,and may in some cases involve determining the amount of torque demandedat the PTO. For instance, if an auxiliary device has been connected tothe PTO and/or the operator requests PTO connection, it may be judgedthat a PTO connection is desired. However, additional or alternativefactors may be taken into account when judging whether or not to connectthe PTO to the transmission.

If it is judged that the PTO should not be connected to the transmission(NO at 404), such as when there is no power request for the PTO, themethod moves to 406. At 406, the method includes sustaining the currenttransmission operating strategy. For instance, the transmission may beheld in its current operating gear by sustaining engagement of one ofthe friction clutches and disengagement of the other friction clutch.Further, one of the clutches in the PTO assembly (e.g., the synchronizer141 shown in FIG. 1 ) may be sustained in a disengaged configuration.

Conversely, if it is judged that the PTO should be connected to receivepower from the transmission (YES at 404), the method moves to 408. At408, the method includes determining if the transmission is operatingunder a low speed condition or if the transmission output speed issubstantially zero. This low speed condition may be a condition wherethe operating speed of the electric machines precludes the PTO frombeing driven to achieve current PTO power demands.

If it is determined that the transmission is not operating under a lowspeed condition (NO at 408) the method moves to 410. At 410, the methodjudges if the transmission is operating under a reverse operatingcondition. The reverse condition may be ascertained using the rotationaldirection of one or more of the electric machines. For instance, aspreviously described, the electric machines have a reverse driverotational direction and an opposite forward drive rotational direction.When the gears 124, 126 on the electric machine output shafts directlymesh with the gear 134, shown in FIG. 1 , the rotational direction ofeach machine in both the forward and reverse drive modes may be oppositeone another. For instance, in the forward drive mode, the first electricmachine may rotate clockwise and the second electric machine may rotatecounter-clockwise or vice versa. However, in other transmissionconfigurations, the electric machines may each rotate in the samedirection in the forward drive mode and may each rotate in the oppositedirection in the reverse drive mode.

If it is determined that the transmission is operating under a low speedcondition (YES at 408) or if it is determined that the transmission isoperating in reverse (YES at 410), the method moves to 412. At 412, themethod includes disengaging (or sustaining disengagement of) the clutchassembly (e.g., the clutch assembly 127, shown in FIG. 1 ) to disconnect(or sustain disconnection of) the first electric machine (e.g., thefirst electric machine 106, shown in FIG. 1 ) from the transmission(e.g., the transmission 104, shown in FIG. 1 ). In this way, one of theelectric machines may be decoupled from the transmission while the othermachine drives the transmission in reverse.

Next at 414, the method includes engaging the clutch (e.g., the clutch141, shown in FIG. 1 ) to couple the PTO (e.g., the PTO 128, shown inFIG. 1 ) and the first electric machine (e.g., the first electricmachine 106, shown in FIG. 1 ). In this way, the first electric machineis used to drive the PTO while the second electric machine andtransmission are operated in the reverse drive mode or while thetransmission is operated at low speeds or at standstill. Consequently,the range of operating conditions over which the PTO may be used isexpanded.

If it is determined that the transmission is not operating in reverse(NO at 410) the method moves to 416. At 416, the method includesengaging (or sustain engagement of) the clutch assembly (e.g., theclutch assembly 127 shown in FIG. 1 ) to connect (or sustain connectionof) the first electric machine (e.g., the first electric machine 106,shown in FIG. 1 ) to the transmission (e.g., the transmission 104, shownin FIG. 1 ). In this way, both the first and second electric machinesmay be used to drive the transmission when it is not operating under alow speed condition or in reverse. After 416 the method moves to 414.Method 400 enables the PTO to be operated across an expansive range ofoperating conditions and permits the system's capabilities with regardto powering auxiliary devices using the PTO to be significantlyexpanded.

The technical effect of the electric driveline system operating methoddescribed herein is to expand the drive system's PTO capabilities andspecifically allow joint PTO operation and reverse drive operation,without constraining the capabilities of the transmission or PTO, ifwanted.

FIGS. 1-2D and 3A-3C show example configurations with relativepositioning of the various components. If shown directly contacting eachother, or directly coupled, then such elements may be referred to asdirectly contacting or directly coupled, respectively, at least in oneexample. Similarly, elements shown contiguous or adjacent to one anothermay be contiguous or adjacent to each other, respectively, at least inone example. As an example, components laying in face-sharing contactwith each other may be referred to as in face-sharing contact. Asanother example, elements positioned apart from each other with only aspace there-between and no other components may be referred to as such,in at least one example. As yet another example, elements shownabove/below one another, at opposite sides to one another, or to theleft/right of one another may be referred to as such, relative to oneanother. Further, as shown in the figures, a topmost element or point ofelement may be referred to as a “top” of the component and a bottommostelement or point of the element may be referred to as a “bottom” of thecomponent, in at least one example. As used herein, top/bottom,upper/lower, above/below, may be relative to a vertical axis of thefigures and used to describe positioning of elements of the figuresrelative to one another.

As such, elements shown above other elements are positioned verticallyabove the other elements, in one example. As yet another example, shapesof the elements depicted within the figures may be referred to as havingthose shapes (e.g., such as being circular, straight, planar, curved,rounded, chamfered, angled, or the like). Additionally, elementsco-axial with one another may be referred to as such, in one example.Further, elements shown intersecting one another may be referred to asintersecting elements or intersecting one another, in at least oneexample. Further still, an element shown within another element or shownoutside of another element may be referred as such, in one example. Inother examples, elements offset from one another may be referred to assuch. Even further, elements which are coaxial or parallel to oneanother may be referred to as such.

The invention will be further described in the following paragraphs. Inone aspect, an electric driveline system is provided that comprises afirst electric machine and a second electric machine mechanicallycoupled to a transmission; and a power take-off (PTO) assembly coupledto the first electric machine and comprising a first clutch coupled to aPTO gearset and designed to selectively disconnect a PTO from the firstelectric machine, wherein the PTO gearset is mechanically coupled to thefirst electric machine.

In another aspect, a method for operation of an electric drivelinesystem is provided that comprises selectively mechanically coupling apower take-off (PTO) to a first electric machine while a second electricmachine transfers mechanical power to a transmission through operationof a first clutch; wherein the second electric machine is mechanicallycoupled to a gear in a transmission gearset; and wherein the firstelectric machine is selectively mechanically coupled to the gear in thegear in the transmission gearset. The method may further comprise, inone example, disconnecting the first electric machine and the PTO fromthe transmission, while the PTO is connected to the first electricmachine, through operation of a second clutch and a third clutch thatare coupled to a gear on an output shaft of the first electric machine.In another example, the method may further comprise, while the firstelectric machine and the PTO are disconnected from the transmission,shifting the transmission between two discrete gear ratios throughoperation of two wet clutches in the transmission. In yet anotherexample, the second electric machine may transfer mechanical power tothe transmission to rotate the transmission in a reverse direction.Further, in another example, the first clutch may be a synchronizer or afriction clutch.

In yet another aspect, an electric driveline system is provided thatcomprises a first electric machine and a second electric machinemechanically coupled to a transmission; and a power take-off (PTO)assembly coupled to the first electric machine and comprising a firstclutch designed to selectively couple an input shaft of a PTO to a PTOgearset, and a second clutch designed to selectively disconnect thefirst electric machine from the transmission.

In any of the aspects of combinations of the aspects, the electricdriveline system may further comprise a second clutch designed toselectively disconnect the first electric machine from the transmission.

In any of the aspects of combinations of the aspects, the electricdriveline system may further comprise a controller includinginstructions that when executed, while the second electric machine istransferring mechanical power to the transmission, cause the controllerto operate the second clutch to disconnect the transmission from thefirst electric machine.

In any of the aspects of combinations of the aspects, the PTO may bedisconnected when the second electric machine is operated to rotate thetransmission in a reverse drive direction.

In any of the aspects of combinations of the aspects, the electricdriveline system may further comprise a controller includinginstructions that when executed, while the electric driveline system isoperated across its speed range, cause the controller to operate thefirst clutch to transfer mechanical power from the first electricmachine to the PTO.

In any of the aspects of combinations of the aspects, the second clutchmay be a friction clutch.

In any of the aspects of combinations of the aspects, the electricdriveline system may further comprise a synchronizer arranged coaxialwith the friction clutch and an output shaft of the first electricmachine.

In any of the aspects of combinations of the aspects, the first clutchmay be designed to selectively couple to a gear to an output shaft ofthe first electric machine; and the gear may mesh with a transmissiongear.

In any of the aspects of combinations of the aspects, the first clutchmay be a synchronizer.

In any of the aspects of combinations of the aspects, the first clutchmay be a wet friction clutch.

In any of the aspects of combinations of the aspects, the transmissionmay be a multi-speed transmission that includes a planetary gearset andtwo friction clutches.

In any of the aspects of combinations of the aspects, the transmissionmay include two outputs coupled to two drive axles.

In any of the aspects of combinations of the aspects, the electricdriveline system may further comprise a controller includinginstructions that when executed, while the second electric machine istransferring mechanical power to the transmission, cause the controllerto: operate the second clutch to disconnect the transmission from thefirst electric machine; and operate the first clutch to transfermechanical power from the first electric machine to the PTO.

In any of the aspects or combinations of the aspects, the secondelectric machine may transfer mechanical power to the transmission torotate the transmission in a reverse direction.

In another representation, a method for operating an electric drive unitis provided that includes selectively engaging a first clutch totransfer power to a power take-off (PTO) from a first electric motor andselectively disengaging a second clutch to inhibit power transfer fromthe first electric motor to a transmission while a second electric motoris providing power to the transmission.

In another representation, an electric drive unit is provided thatincludes a first electric machine and a PTO system designed to connectand disconnect a PTO from the first electric machine based on one ormore operating conditions and a second electric machine designed totransfer mechanical power to a transmission while the first electricmachine is connected and disconnected from the PTO.

Note that the example control and estimation routines included hereincan be used with various powertrain, electric drive, and/or vehiclesystem configurations. The control methods and routines disclosed hereinmay be stored as executable instructions in non-transitory memory andmay be carried out by the control system including the controller incombination with the various sensors, actuators, and other transmissionand/or vehicle hardware in combination with the electronic controller.As such, the described actions, operations, and/or functions maygraphically represent code to be programmed into non-transitory memoryof the computer readable storage medium in the vehicle and/or drivelinecontrol system. The various actions, operations, and/or functionsillustrated may be performed in the sequence illustrated, in parallel,or in some cases omitted. Likewise, the order of processing is notnecessarily required to achieve the features and advantages of theexamples described herein, but is provided for ease of illustration anddescription. One or more of the illustrated actions, operations and/orfunctions may be repeatedly performed depending on the particularstrategy being used. One or more of the method steps described hereinmay be omitted if desired.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevant artsthat the disclosed subject matter may be embodied in other specificforms without departing from the spirit of the subject matter. Theembodiments described above are therefore to be considered in allrespects as illustrative, not restrictive. As such, the configurationsand routines disclosed herein are exemplary in nature, and that thesespecific examples are not to be considered in a limiting sense, becausenumerous variations are possible. For example, the above technology canbe applied to powertrains that include different types of propulsionsources including different types of electric machines, internalcombustion engines, and/or transmissions. The subject matter of thepresent disclosure includes all novel and non-obvious combinations andsub-combinations of the various systems and configurations, and otherfeatures, functions, and/or properties disclosed herein.

As used herein, the term “substantially” is construed to mean plus orminus five percent of the range, unless otherwise specified.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

The invention claimed is:
 1. A method for operation of an electricdriveline system, comprising: mechanically coupling a power take-off(PTO) to a first electric machine via engagement of a first synchronizercoupled to a PTO input shaft while a second electric machine transfersmechanical power to a transmission; and mechanically coupling the firstelectric machine to the transmission via operation of a secondsynchronizer and a first friction clutch that are coupled to a gear onan output shaft of the first electric machine; wherein the secondelectric machine is mechanically coupled to a gear in the transmission;and wherein the first electric machine is selectively mechanicallycoupled to the gear in the transmission gearset.
 2. The method of claim1, further comprising: disconnecting the first electric machine and thePTO from the transmission, while the PTO is connected to the firstelectric machine, through disengagement of the second synchronizer andthe first friction clutch.
 3. The method of claim 2, further comprising,transferring mechanical power from the transmission to a first driveaxle and a second drive axle via engagement of a first disconnect clutchand a second disconnect clutch coupled to an output shaft of thetransmission.
 4. The method of claim 1, wherein the second electricmachine transfers mechanical power to the transmission to rotate thetransmission in a reverse drive direction while the second synchronizerand the first friction clutch are engaged.
 5. The method of claim 1,wherein the transmission includes: a planetary gearset positionedcoaxial to the gear in the transmission and a third synchronizer and asecond friction clutch that selectively brake a ring gear in theplanetary gearset.